Abstract Black carbon (BC) constitutes a refractory carbon (C) pool in soil and other environments. Estimating the amount and dynamics of BC in soil is important in terms of the global C cycle. The goal of this study was to characterize the contribution of BC to total and aromatic C in a variety of soils using the benzene polycarboxylic acid (BPCA) method and solid-state 13C nuclear magnetic resonance (NMR) spectroscopy. Thirteen A-/Ap (plowed layer)-horizon soils that belong to widely distributed soil series (Humic Andosols, Dystric Cambisols, Gleyic Cambisols, Eutric Fluvisols, and Dystric Planosols) under typical land uses (forest, grassland, upland field, and paddy field) in Japan and two Andosol profiles were analyzed. Three humic acid samples including the green fraction, which contains 4,9-dihydroxyperylene-3,10-quinone (DHPQ) as a chromophore and has mycorrhiza as a possible source (referred to as Pg), were also subjected to the BPCA procedure. The BC content in the 13 A-/Ap-horizon soils was 0.3–53 gC kg−1 or 5.7–48% of the total soil C (BC%). The BC content correlated positively with the total C content and with aromatic C content, while the relationship between BC% and soil order or land use was not clear. An analysis of Pg suggested the potential contribution of DHPQ to the yield of benzenehexacarboxylic acid in the BPCA method. The variations in BC content and C composition of two Andosol profiles indicated a greater stability of BC than the other types of C, including monocyclic aromatic C. The contribution of BC to aromatic C in their lower layers was estimated to be ca. 55–70% based on a regression equation when assuming that 70–90% of the BC was aromatic C.

中文翻译：

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黑碳作为表层土壤中芳香碳的重要组成部分，其重要性在火山灰土壤剖面中得到增强

摘要 黑碳 (BC) 在土壤和其他环境中构成难熔碳 (C) 库。就全球碳循环而言，估算土壤中碳链的数量和动态非常重要。本研究的目的是使用苯多羧酸 (BPCA) 方法和固态 13C 核磁共振 (NMR) 光谱表征 BC 对各种土壤中总碳和芳香碳的贡献。13 种 A-/Ap（耕作层）-水平土壤，属于典型土地利用（森林、草地、旱地和稻田）下广泛分布的土壤系列（腐殖质干土、Dystric Cambisols、Gleyic Cambisols、Eutric Fluisols 和 Dystric Planosols）场），并分析了两个 Andosol 剖面。三个腐植酸样品，包括绿色部分，其中含有 4,9-dihydroxyperylene-3，10-醌 (DHPQ) 作为生色团并具有菌根作为可能的来源（称为 Pg），也进行了 BPCA 程序。13 A-/Ap-horizo​​n 土壤中的 BC 含量为 0.3-53 gC kg-1 或总土壤 C (BC%) 的 5.7-48%。BC 含量与总碳含量和芳香碳含量呈正相关，而 BC%与土壤秩序或土地利用之间的关系尚不明确。Pg 的分析表明 DHPQ 对 BPCA 方法中苯六甲酸的产率有潜在贡献。两个 Andosol 剖面的 BC 含量和 C 组成的变化表明 BC 比其他类型的 C 具有更大的稳定性，包括单环芳族 C。BC 对它们下层中芳族 C 的贡献估计为大约。